The invention generally relates to synthetic fiber constructions having particular physical characteristics. More specifically, the invention relates to multi-component synthetic fibers having a particular component arrangement known as an xe2x80x9cisland-in-seaxe2x80x9d arrangement, which can be readily and easily manufactured, and which provides desirable preselected physical properties.
Synthetic fibers are widely utilized in a variety of end uses, including industrial uses, the manufacture of apparel, home furnishings, and the like. The use of synthetic fibers has grown tremendously over the years due in part to their consistency and uniformity. In other words, natural fibers generally vary from fiber to fiber while synthetic fibers, when produced under properly controlled conditions, can be produced to be consistent and to have desired cross-sectional shapes and the like.
Some common methods for producing synthetic fibers include melt and solution spinning. In melt spinning, the fiber-forming material (generally a polymeric material) is melted until it is flowable, then extruded through a spinneret to form filaments of a desired cross-section and diameter. The thus-extruded filaments are then quenched (i.e. cooled) in some manner, such as by contacting them with cool air, drawing them through a liquid bath, etc., to solidify them. These filaments can be used in this form or processed further, such as by drawing them, texturing them, or the like. Similarly, solution spinning also involves the extrusion of a flowable material, with the material in that case being made flowable by providing it or rendering it in solution form.
In the production of some synthetic fibers, it sometimes results that a single polymeric material cannot provide all of the physical properties desired for a particular end use. Therefore, multicomponent fibers have been developed, which enable the physical properties of a plurality of materials to be combined in one fiber. One common type of multicomponent fiber is the sheath/core fiber. In sheath/core fibers, the spinneret is designed so that it feeds a first material to the center of the filament, and a second material so that it forms a sheath covering the first material. Another common type of multicomponent fiber is the side-by-side filament, in which a first material forms one side of the filament and a second material forms the second filament side. These types of filaments are commonly used in the production of crimped yarns, with the first and second materials being selected to behave differently in response to quenching or drawing so that they become crimped during the subsequent manufacturing steps.
Some of the above-mentioned multicomponent sheath/core fibers have so-called xe2x80x9cislands-in-seaxe2x80x9d orientations. The xe2x80x9cseaxe2x80x9d component forms the sheath, with the xe2x80x9cislandxe2x80x9d components being the core or cores. Islands-in-sea fibers are known, in which one or more elastomeric core components are surrounded by a sheath designed to be soluble so that when it is removed, the resulting composite structure has one or more elastomeric cores surrounded by a plurality of fine non-elastic ultra-fine fibers. Other fiber orientations are known where two or more different types of material comprise the islands. In such composite fibers, when the sea is removed, super-fine filaments of more than one type are produced.
Islands-in-sea fiber technology has been applied to composite materials where the island material needs protection from outside elements via the sea material, such as, for example, to prevent the core materials that may be abrasive from damaging the material-producing equipment. Various sea configurations are known affecting the mechanical strength of the multicomponent product as a whole. Further, it is known that the core and sheath portions can be composed of either the same kind or different kinds of polymers.
In one embodiment, the present invention is directed to the production of fibers which can achieve a plurality of physical characteristics and which can be readily and efficiently produced.
In another embodiment, the present invention is directed to multicomponent fibers in which a plurality of geometrically-shaped cores of a first polymeric material are provided within a sea of a second polymeric material, with the second polymeric material forming a plurality of spokes which converge in the center of the fiber. Each of the geometrically shaped cores desirably includes at least two substantially straight sides, and the fibers desirably are circular in cross section. In this way, the cores are preferably formed as a plurality of pie-shaped pieces surrounded by the sea of the second material. The fibers of the present invention are designed to be used in their multicomponent form, with the sea being retained intact during the use of the fiber. In other words, the sea is selected from a material is insoluble in all media which it is designed to encounter, unlike the prior art constructions in which the sea is designed to be dissolved to leave a plurality of independent cores.
According to one embodiment of the present invention, the fibers of the present invention include an outer, or sheath material extending continuously to a central core made from the same material. The continuous connection results in a spoke-like effect, with spokes extending between the generally pie-shaped islands. As a result, the sea material can enhance the fiber resilience and rigidity.
In another aspect of the invention, the sea and island-forming polymeric materials are selected so that the resulting fibers have predetermined visual and refractive properties. For example, a comparatively expensive sea polymer may be selected to have high resiliency and dyeability properties while the islands are formed from a less expensive polymer or a polymer material having a refractive index, which is different from that of the sea-forming material. In this embodiment, the multiple angles formed by the sheath and the spokes of the sea polymer provide surfaces for light scattering. In this way, a fiber having soil-hiding capabilities can be readily achieved that performs better than conventional trilobal soil-hiding performance yarns. Such yarns are desirable in the carpet market, where a sea could be produced from a polymer having good resilience and dyeability, while a less expensive material could be used to form the islands.
In a still further embodiment, the present invention relates to a method for manufacturing a two component island-in-sea fiber. An apparatus for forming synthetic fibers in a spinning direction is provided. The apparatus has a distribution plate oriented perpendicular to the spinning direction, and defines a flow path generally perpendicular to said spinning direction. The plate further has an exit hole extending generally parallel to said spinning direction. A metering plate is positioned downstream of the distribution plate, is oriented in a direction generally perpendicular to the spinning direction, and includes an exit hole extending generally parallel to the spinning direction. The metering plate exit hole forms a common flow path with the distribution plate exit hole. The metering plate exit hole is adapted to moderate the pressure of a material flowing from the distribution plate exit hole through the metering plate exit hole to provide flow of material to a spinneret with a more consistent pressure. The flow of a plurality of materials is directed through the apparatus to form a two-component material having a substantially uniform two-component cross-section.